Background: Prognosis of appendiceal adenocarcinoma patients is based on burden of disease, histology, and nature of therapy, which remains static despite time in follow-up. We hypothesized that conditional survival provides an informative metric that allows patients better understanding of their disease.
Methods: Using the Surveillance, Epidemiology and End Results database, patients with appendiceal adenocarcinoma from 1988 to 2012 were included. Actuarial Life table analyses and Kaplan-Meier curves were used for statistical inference.
Results: Of 5,952 patients, the median age was 60 years (IQR 50-72) and 52 % were female. Histologies included were adenocarcinoma (NOS 37 %), mucinous adenocarcinoma (MA 53 %), and signet ring cell (SRC 10 %). Five-year overall survival (OS) at diagnosis for patients with metastatic disease was 11 % (NOS), 45 % (MA), and 8 % (SRC), respectively. Annual conditional probability of survival from years 1-5 after diagnosis for patients with SRC with metastatic disease was 55, 60, 68, 55, and 82 % compared with 84, 86, 86, 88, and 92 % with MA. Probability of surviving the first year after extended surgery was 77 % (NOS), 85 % (MA), and 75 % (SRC). Those that survived 5 years after surgery had a 94 % (NOS), 93 % (MA), and 86 % (SRC) probability of surviving the sixth year.
Conclusions: In the setting of dismal cumulative probability of survival (or overall survival), conditional probability is more informative in providing prognostication. This distinction might be important for patients especially with SRC who may live in constant fear of disease. Such data can be used to reassure patients and perhaps modify surveillance strategies for patients.